The Flock had an interesting gimmick: The game would be removed from sale once a finite number of player lives had been lost in-game.
"At that point, only the people who own The Flock on Steam will be able to experience its "climactic finale," the game's developer said in a press release. After that event The Flock will "go offline permanently and no longer be playable." What exactly happened is that very few people bought the game, and launch reviews were almost universally bad.
The game was, by any metric, a failure.
Creative Director and Game Designer Jeroen Van Hasselt gave this 30 minute talk about what happened, and what they learned from the experience. There are a number of good lessons in here including the reality that a high level of press interest won't automatically translate into reviews, nor sales. He also stresses that you have to be competitive with other games available near, or below, your price point.
If you want to see what it takes to look failure in the eyes and keep going, this is a good place to start.